For now the speaker cables are doing a great job. I've wiggled them a few times and they're not going anywhere. The wires haven't pulled out from the binding posts at all, however I do have an idea.
Here's my idea. I want to either find or fashion a wedge to put underneath the speakers so the whole bottom surface is in contact with something solid. Then get a small, thin black nylon strap that I can cinch tight without sticking out like a sore thumb. Dunno where I might find such a strap, but I'm sure there's something out there that will work for me.
What about using isolation pads? How spongy are they? Will they just squish down from the pressure of the strap?